Session four
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This document discusses data operators and attributes in VHDL. It describes concatenation and aggregate operators used to merge arrays and assign values. Examples show shifting and rotating registers using concatenation. Attributes allow returning information about entities, types, and signals like 'left, 'right, 'high, and 'length. The document contains exercises writing VHDL statements and an example using attributes to return values in a process. It also mentions using Modelsim to simulate sequential circuits with registered outputs appearing on the next clock cycle.
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Session four
- 1. http://www.bized.co.uk Session 4 Prepared by Alaa Salah Shehata Mahmoud A. M. Abd El Latif Mohamed Mohamed Tala’t Mohamed Salah Mahmoud Version 02 – October 2011 Copyright 2006 – Biz/ed
- 2. http://www.bized.co.uk 4 -Data Operators -Aggregate Contents -Concatenation -Attributes -LABs -Counters -Rotating LEDs 2 Copyright 2006 – Biz/ed
- 3. Session 4 http://www.bized.co.uk Data Operators 3 Copyright 2006 – Biz/ed
- 4. Session 4 http://www.bized.co.uk Data Operators Concatenation Used to merge two operands together using the concatenation operator (&). This result is an array in which length is the sum of lengths of both operands. C <= A & B A B C 4 Copyright 2006 – Biz/ed
- 5. Session 4 http://www.bized.co.uk Shift registers Example 19 5 Copyright 2006 – Biz/ed
- 6. Session 4 http://www.bized.co.uk Data Operators Concatenation A7 A0 Shift Right Register: A <= „0‟ & A(7 downto 1); 0 A7 A1 A7 A0 Shift Left Register: A <= A(6 downto 0) & „0‟ ; 0 A6 A0 6 Copyright 2006 – Biz/ed
- 7. Session 4 http://www.bized.co.uk Data Operators Concatenation A7 A0 Shift Right Register: A <= A(7) & A(7 downto 1); A7 A7 A1 we use this shifting when we need to keep the sign in our vector and not losing it. A7 A7 A7 A2 7 Copyright 2006 – Biz/ed
- 8. Session 4 http://www.bized.co.uk Rotating registers Example 20 8 Copyright 2006 – Biz/ed
- 9. Session 4 http://www.bized.co.uk Data Operators Concatenation A7 A0 Rotate Right Register: A <= A(0)& A(7 downto 1); A0 A7 A1 A7 A0 Shift Left Register: A <= A(6 downto 0) & A(7); A6 A0 A7 9 Copyright 2006 – Biz/ed
- 10. Session 4 http://www.bized.co.uk Data Operators Aggregate Provides an easy way of assigning objects of composite types The aggregate assigns values to a selected elements of an array or a record. Example 20 Signal data_bus : std_logic_vector(15 downto 0); data_bus <= (15 downto 8 => '0' , others => '1'); “0000000011111111” data_bus <= (1 | 4 | 7 => '1', 2 | 3 => '0', others => 'Z'); “ZZZZZZZZ1ZZ1001Z” data_bus <= (others => ‘Z'); -- fill data_bus with ones “ZZZZZZZZZZZZZZZZ” 10 Copyright 2006 – Biz/ed
- 11. Session 4 http://www.bized.co.uk Exercise 5 11 Copyright 2006 – Biz/ed
- 12. Session 4 http://www.bized.co.uk Write the statement “0000000100000000” --16bit “11111111” --8 bits “11110011” --8bits 12 Copyright 2006 – Biz/ed
- 13. Session 4 http://www.bized.co.uk Write the statement “0000000100000000” --16bit data_bus <= ( 8 => ‘1’ , others => ‘0’ ) ; “11111111” --8 bits data_bus <= (others => ‘1’ ) ; “11110011” --8bits data_bus <= ( 3|2 => ‘0’,others => ‘1’ ) ; 13 Copyright 2006 – Biz/ed
- 14. Session 4 http://www.bized.co.uk Attributes Attribute Return value Attributes allow returning information about entities , architectures , types , signals Count’left 0 „left, „right, „high, „length, ‟range, „event, … States’left Idle Word’left 15 Note Pronounce the apostrophe as “tick “ Count’right 127 States’right Write Example Word’right 0 Type count is integer range 0 to 127 ; Count’high 127 States’high Write Type states is ( idle , decision , read , write ) ; Word’high 15 Type word is array ( 15 downto 0 ) of std_logic ; Count’low 0 Note States’low Idle As we know if we need to ask about the rising edge of the clk we Word’low 0 can say if rising_sdge(clk) then Count’length 128 States’length 4 by using attributes we also can ask about the clk with other formula Word’length 16 that says if (clk’event and clk = ‘1’) then 14 Copyright 2006 – Biz/ed
- 15. Session 4 http://www.bized.co.uk • General example on Attributes Example 21 15 Copyright 2006 – Biz/ed
- 16. Session 4 http://www.bized.co.uk ARCHITECTURE examp OF attrs IS Type myInt is range 0 to 15; Type states is (red, yellow, green); Type word is array (15 downto 0) of std_logic; Signal count: integer; signal mySig: myInt; signal state : states; BEGIN process begin mySig <= myInt'left; count <= word'left; state <= states'left; wait for 10 ns; mySig <= myInt'right; count <= word'right; state <= states'right; wait for 10 ns; mySig <= myInt'low; count <= word'low; state <= states'low; wait for 10 ns; mySig <= myInt'high; count <= word'high; state <= states'high; wait for 10 ns; count <= word'length; wait; end process; END ARCHITECTURE examp; 16 Copyright 2006 – Biz/ed
- 17. Session 4 http://www.bized.co.uk Sequential Circuits on Modelsim 17 Copyright 2006 – Biz/ed
- 18. Session 4 http://www.bized.co.uk As clock is found in your design.. the output registered (saved) and appeared next clk cycle 18 Copyright 2006 – Biz/ed
- 19. Session 4 http://www.bized.co.uk • 4-Bit binary Counter lab 5 19 Copyright 2006 – Biz/ed
- 20. Session 4 http://www.bized.co.uk • 4-Bit binary Counter with asynchronous load lab 6 20 Copyright 2006 – Biz/ed
- 21. Session 4 http://www.bized.co.uk Assignment Session-4 4-Bit binary Up-Down Counter with asynchronous load 21 Copyright 2006 – Biz/ed
- 22. Session 4 http://www.bized.co.uk • One way rotating LEDs lab 7 22 Copyright 2006 – Biz/ed
- 23. Session 4 http://www.bized.co.uk Assignment Session-4 Two Ways Rotating LEDs 23 Copyright 2006 – Biz/ed
- 24. Session 4 http://www.bized.co.uk Download Session 4 material Session 4.pdf Labs4.txt Ask for the material through mail start.courses@gmail.com Facebook group start.group@groups.facebook.com 24 Copyright 2006 – Biz/ed
- 25. Session 4 http://www.bized.co.uk Questions Session-4 25 Copyright 2006 – Biz/ed
- 26. Session 4 http://www.bized.co.uk Take Your Notes Print the slides and take your notes here --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- 26 Copyright 2006 – Biz/ed
- 27. Session 4 http://www.bized.co.uk Take Your Notes Print the slides and take your notes here --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- --------------------------------------------------------------------------------------------------------------------------------------------- 27 Copyright 2006 – Biz/ed
- 28. Session 4 http://www.bized.co.uk See You Next Session 28 Copyright 2006 – Biz/ed